The major objective of this research proposal is to determine the biochemical characteristics and covalent structure of basement membrane collagens from normal and diabetic human kidney. Kidneys will be obtained at the time of autopsy. The whole kidney will be homogenized and digested with pepsin. The collagens, type I and III, will be removed by salt precipitation. The basement membrane collagens will be separated out by further addition of salt to the supernatant. After purification of basement membrane collagens various polypeptide chains will be isolated and purified by combination of molecular sieve and ion exchange chromatography. The various polypeptide chains will be characterized as regards to amino acid composition, cyanogen bromide peptides, the degree of hydroxylation of lysine residues and glycosylation of hydroxylysine residue. The amino acid sequence of the cyanogen bromide peptides will be determined in order to obtain the covalent structure of the various polypeptide chains. Collagen is one of the major components of glomerular basement membrane. A definitive understanding of its chemical structure is essential to provide better understanding in the normal and diabetic state. This research project is devoted to fulfilling this need.